Portion of a mask



FIG. 1 is an exploded, perspective view of a portion of a mask according to our design; and,

FIG. 2 is a front view thereof.

The broken lines showing environment or structure are for illustrative purposes only and form no part of the claimed design.

The dash-dot lines indicate the border between claimed and unclaimed subject matter and form no part of the claimed design.

The dotted lines on the straps/yokes represent unclaimed stitching.

The use of stippling in FIGS. 1-2 is used to indicate shading and/or contrasting materials compared to the line-shaded portion of the design. 

The ornamental appearance of a portion of a mask, as shown and described. 